Results: 8

Mean protein concentration of skimmed milks from C57BL/6J and SEG/Pas mice, at 10 days of lactation. The number of mice used in each population is given in parentheses. Error bars correspond to the standard error.

Alignment of nucleotide and amino acid sequences of C57BL/6J and SEG/Pas Wap. The deduced amino acid sequence is given above according to the one-letter code. Horizontal arrows indicate the position and orientation of primers used for amplification. Pink frames show the SNP between C57BL/6J and SEG/Pas and blue frames indicate the translation-initiation and termination codon. Red amino acid residues in SEG/Pas sequence represent amino acid substitutions (K36E, T94A, M99K); Δ represents the loss of the serine in position 93.

Alignment of the amino acid sequence of β-casein as deduced from the cDNA obtained from C57BL/6J and SEG/Pas. Peptides sequences are split into blocks of amino acid residues to visualize the exonic modular structure of the protein as deduced from known splice junctions of the Mus musculus sequence. Red amino acids in C57BL/6J sequence indicate the amino acid substitutions in SEG/Pas sequence. A* depicts a conservative mutation in the corresponding codon (GCC-> GCT in M. spretus). The pink vertical arrow indicates the deletion of a Q residue arising in the 6th exon, during the course of the splicing process in C57BL/6J and SEG/Pas mouse strains.

Schematic representation of the genomic region spanning exon 14 to exon 18 of the gene encoding αs1-casein in cow and mouse. Diagonally hatched block and segment in the cow genome indicate exon 16 and a part of the downstream intron which is first duplicated in the mouse genome (pink arrow). This first duplication (yellow block) is duplicated in tandem seven times in the mouse genome (blue arrow). The green block indicates exon 15 existing only in cattle, sheep and goats. The red intronic segment (30 nucleotides) appears to be conserved between several species (cattle, mice, pigs and humans). In addition in mice, there is a 350-nucleotides insertion between exon 16.14 and 17, contributing to enlarge this genome segment, as compared with cow (3 kb vs. 2 kb).